Monoclonal antibodies to human hemopoietic precursor cell and/or leukemic cell antigens will be raised using a mouse-mouse cell hybridoma technique. Human brain, null ALL cells and light density CML cells will be used as immunogens. Supernatants from the hybridoma clones will be tested for the presence of antibodies and the antibodies specificities using an ELISA (enzyme-linked immunosorbant assay) and a modified ELISA. In the modified ELISA, normal hemopoietic precursor cells, null ALL cells, CML cells and normal peripheral blood cells will be used as targets. Selected clones will be cultured for the production of large quantities of monoclonal antibodies. These atibodies will be tested for their reactivity to normal hemopoietic precursor cells using the following in vitro assays: CFC-GM (colony-forming cells - granulocyte, macrophage), BFU-E (burst-forming units - erythroid) and Dexter suspension cultures (long term surviving hemopoietic precursors). The reactivity of the antibodies to the leukemic populations of ALL, AUL, AML, AMML, CLL, CML and CML-BC will be tested by various immunologic techniques (complement fixation, modified ELISA and immunofluorescence). The quality of antibody bound to various normal and leukemic cell types will be done using a FACS (fluorescence-activated cell sorter). These studies will determine if the monoclonal antibodies can be used to separate leukemic cell populations from normal hemopoietic precursor cell populations. Preparative, highly selective separation methodology can then be developed for use in our autologous bone marrow transplantation program.